1. Field of the Invention
The present invention relates generally to an ultrasonic probe used in an underwater ultrasonic sensor, ultrasonic diagnostic equipment, or the like.
2. Related Background Art
An ultrasonic probe is used in a fish finder, ultrasonic diagnostic equipment for living bodies, and the like. In such an ultrasonic probe, an acoustic lens is used for converging a ultrasonic beam to improve resolution. A conventional acoustic lens material is described in JP 62( 1987)-90139 A. Preferably, an acoustic lens used in an ultrasonic probe for ultrasonic diagnostic equipment, particularly for living bodies, is formed in a convex shape so that close contact with a living body is achieved. Therefore, the acoustic lens is required to have a lower acoustic velocity than that (about 1.54 km/s) of a living body. Furthermore, in order to minimize the reflection of ultrasonic waves between the acoustic lens and a living body, it is necessary for the acoustic lens to have an acoustic impedance close to that (about 1.54 Mrayl) of the living body. Conventionally, as a material for the acoustic lens, one containing silicone rubber as the main material to which powder of titanium oxide, alumina, or the like is added has been used (JP 5( 1993)-34011 B).
The silicone rubber to which titanium oxide, alumina or the like is added, which has been used conventionally, has an acoustic impedance of about 1.6 Mrayl, which substantially satisfies the required condition. In the silicone rubber, however, since the ultrasonic waves are attenuated considerably, there has been a problem of degradation in ultrasonic transmission and reception sensitivity.
The present invention is intended to solve the above-mentioned conventional problem. It is an object of the present invention to provide an ultrasonic probe whose performance such as, for example, sensitivity and frequency characteristics, is not degraded due to the use of an acoustic lens having an acoustic impedance close to that of water or a living body and a low attenuation level.
In order to achieve the above-mentioned object, an ultrasonic probe according to the present invention includes a piezoelectric element for transmitting and receiving ultrasonic waves and an acoustic lens provided on an ultrasonic transmission/reception side of the piezoelectric element. The acoustic lens is formed by vulcanization through addition of 2,5-dimethyl-2,5-di-t-butyl peroxy hexane as a vulcanizing agent to a composition prepared by addition of silica (SiO2) particles in an amount of 40 wt % to 50 wt % to silicone rubber with a dimethylpolysiloxane structure including vinyl groups.
A method of manufacturing an ultrasonic probe of the present invention is directed to a method of manufacturing an ultrasonic probe including a piezoelectric element for transmitting and receiving ultrasonic waves and an acoustic lens provided on an ultrasonic transmission/reception side of the piezoelectric element. The method is characterized in that the acoustic lens is formed by at least one vulcanizing formation method selected from press molding and cast molding through addition of 2,5-dimethyl-2,5-di-t-butyl peroxy hexane as a vulcanizing agent to a composition prepared by addition of silica (SiO2) particles in an amount of 40 wt % to 50 wt % to silicone rubber with a dimethylpolysiloxane structure including vinyl groups.
An acoustic lens of the present invention is characterized by being formed in an acoustic lens shape by vulcanization formation through addition of 2,5-dimethyl-2,5-di-t-butyl peroxy hexane as a vulcanizing agent to a composition prepared by addition of silica (SiO2) particles in an amount of 40 wt % to 50 wt % to silicone rubber with a dimethylpolysiloxane structure including vinyl groups.
A method of manufacturing an acoustic lens according to the present invention is characterized in that the acoustic lens is formed by at least one vulcanizing formation method selected from press molding and cast molding through addition of 2,5-dimethyl-2,5-di-t-butyl peroxy hexane as a vulcanizing agent to a composition prepared by addition of silica (SiO2) particles in an amount of 40 wt % to 50 wt % to silicone rubber with a dimethylpolysiloxane structure including vinyl groups.